Abstract: As a kind of planar defect, stacking faults are seldom explored. Quantitatively evaluating the correlation between stacking faults (SFs) and strength remains unclear. In the present work, we conducted tensile tests at specified true strains and characterized deformation microstructures for a nonequiatomic CoCrNi alloy with very low stacking fault energy (SFE). Characteristics of stacking fault spacing, stacking fault density, and stacking fault strengthening quantification were investigated. This work provides a reasonable reference for the quantitative calculation of stacking fault strengthening.